DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2022-0991; Project Identifier AD-2022-00155-T;
Amendment 39-22299; AD 2023-01-05]
Airworthiness Directives; Learjet, Inc., Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
SUMMARY: The FAA is adopting a new airworthiness directive (AD)
certain Learjet, Inc., Model 45 airplanes. This AD was prompted by a
determination that new or more restrictive airworthiness limitations
are necessary. This AD requires revising the existing inspection
program to incorporate reduced inspection intervals for the anti-ice
manifold assembly. The FAA is issuing this AD to address the unsafe
condition on these products.
DATES: This AD is effective March 9, 2023.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of March 9,
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2022-0991; or in person at Docket Operations between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD
docket contains this final rule, any comments received, and other
information. The address for Docket Operations is U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Material Incorporated by Reference:
For service information identified in this final rule,
contact Learjet, Inc., One Learjet Way, Wichita, KS 67209-2942;
telephone 316-946-2000; fax 316-946-2220; email
email@example.com; website bombardier.com.
You may view this service information at the FAA,
Airworthiness Products Section, Operational Safety Branch, 2200 South
216th St., Des Moines, WA. For information on the availability of this
material at the FAA, call 206-231-3195. It is also available at
regulations.gov under Docket No. FAA-2022-0991.
FOR FURTHER INFORMATION CONTACT: Adam Hein, Aerospace Engineer,
Mechanical Systems and Propulsion Section, FAA, Wichita ACO Branch,
1801 S Airport Road, Wichita, KS 67209; telephone (316) 946-4116;
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain Learjet, Inc.,
Model 45 airplanes. The NPRM published in the Federal Register on
August 11, 2022 (87 FR 49556). The NPRM was prompted by a determination
that new or more restrictive airworthiness limitations are necessary.
In the NPRM, the FAA proposed to require revising the existing
inspection program to incorporate reduced inspection intervals for the
anti-ice manifold assembly.
The FAA issued a supplemental notice of proposed rulemaking (SNPRM)
to amend 14 CFR part 39 by adding an AD that would apply to certain
Learjet, Inc., Model 45 airplanes. The SNPRM published in the Federal
Register on November 10, 2022 (87 FR 67834). The SNPRM was prompted by
a determination that additional airplanes needed to be added to the
applicability. The SNPRM proposed to require revising the existing
inspection program to incorporate reduced inspection intervals for the
anti-ice manifold assembly and to add airplanes to the applicability.
The FAA is issuing this AD to address metal fragments breaking off the
anti-ice manifold assembly due to fatigue, which could block a duct in
the anti-ice system and result in an unannunciated loss of ice
protection and subsequent loss of control of the airplane.
The FAA issued AD 2001-03-05, Amendment 39-12109 (66 FR 10353,
February 15, 2001) (AD 2001-03-05), for certain Learjet Model 45
airplanes. AD 2001-03-05 requires, among other actions, revising the
existing Learjet 45 maintenance program to incorporate additional
inspections and maintenance practices for the anti-ice manifold
assembly, including a 600-hour repetitive inspection interval of an
earlier design/part number of the anti-ice manifold. Since the FAA
issued AD 2001-03-05, the anti-ice manifold was redesigned, and the
inspection interval was extended to 1,200 flight hours. The design
approval holder subsequently determined that the design improvements
made to the anti-ice manifold assembly did not fully address the
original issue of vane cracking, so the 1,200-hour inspection on the
redesigned part is insufficient. However, the FAA determined that a
repetitive inspection interval of 600 flight hours is sufficient to
address the unsafe condition. Therefore, this AD requires revising the
existing inspection program to incorporate a reduced 600-hour
inspection interval for the redesigned part. Accomplishing the required
actions in this AD terminates the requirements of paragraph (c) of AD
Discussion of Final Airworthiness Directive
The FAA received comments from two individuals who supported the
SNPRM without change.
The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes, this
AD is adopted as proposed in the SNPRM. None of the changes will
increase the economic burden on any operator.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Learjet 40 Maintenance Manual Temporary Revision
(TR) 04-33 and Learjet 45 Maintenance Manual TR 04-48, both dated
January 18, 2022. This service information specifies reduced inspection
intervals for the anti-ice manifold assembly. These documents are
distinct since they apply to different airplane configurations. This
service information is reasonably available because the interested
parties have access to it through their normal course of business or by
the means identified in ADDRESSES.
Costs of Compliance
The FAA estimates that this AD affects 481 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:
|Inspection program revision
||1 work-hour x $85 per hour =
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: General requirements.
Under that section, Congress charges the FAA with promoting safe flight
of civil aircraft in air commerce by prescribing regulations for
practices, methods, and procedures the Administrator finds necessary
for safety in air commerce. This regulation is within the scope of that
authority because it addresses an unsafe condition that is likely to
exist or develop on products identified in this rulemaking action.
This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
(2) Will not affect intrastate aviation in Alaska, and
(3) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness